CFCs, various properties

CFC s, global warming potential, 14-34 to 35 CFC s, various properties, 6-133 to 135 Characteristic Bond Lengths in Free Molecules, 9-48... 

Research and development programs have been initiated by the cellular plastics industry to develop viable substitute blowing agents. These must have similar or improved properties to their CFC counterparts at a reasonable cost. Emphasis was initially placed on HCFC 123 and HCFC 141b, both having much shorter lifetimes and considerably less effect (up to 50 times) on o2one layer depletion (22). However, various options, including gas mixtures, water, or CO2 blown foams, continue to be studied ultimately to eliminate all CFCs and HCFCs. 

Chlorotrifluoroethylene monomer serves as a building block for the CTFE telomer oils as well as the solid higher polymer and various copolymers. CFC-113 also may be used in the production of trifluoroethylene monomer by vapor-phase reduction using hydrogen and a precious metal catalyst, usually palladium [reaction (9)]. Copolymers of trifluoroethylene and vinylidene fluoride show interesting piezoelectric properties. 

For their physical properties, high stability and low toxicity, chlorofluorocarbons (CFC s) have found an extensive use, accompanying the development of various industrial fields. About forty years after their discovery in the early thirties [1], the hypothesis was advanced that, because of their stability, these compounds dispersed in the atmosphere arrived in the stratosphere where they caused a series of reactions generating chlorine and leading to an abnormal consumption of the ozone layer [2]. The Protocol of Montreal and its successive amendments have therefore placed limits to the production and the use of CFCs proscribed in industrialized coimtries since 1996 and fi om 2010 in the underdeveloped nations. 

What properties of CFCs make them ideal for various commercial applications but also make them a long-term problem in the stratosphere ... 

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